folone

/**
 * <b>Fixed Point Combinator is:</b>
 * Y = λf.(λx.f (x x)) (λx.f (x x))
 * 
 * <b>Proof of correctness:</b>
 * Y g  = (λf . (λx . f (x x)) (λx . f (x x))) g    (by definition of Y)
 * = (λx . g (x x)) (λx . g (x x))                  (β-reduction of λf: applied main function to g)
 * = (λy . g (y y)) (λx . g (x x))                  (α-conversion: renamed bound variable)
 * = g ((λx . g (x x)) (λx . g (x x)))              (β-reduction of λy: applied left function to right function)
 * = g (Y g)                                        (by second equality) [1]

bwmcadams

import com.mongodb.casbah.Imports._

val conn = MongoConnection()

val db = conn("test")

val coll = db("foo")

for (x <- coll.find(MongoDBObject("_id" -> new ObjectId("4cd2d357c575954934c5a975")), 
          MongoDBObject("x" -> 1))) println(x)